KR100611170B1 - Reception device and method of reception timing detection - Google Patents

Abstract

SUMMARY OF THE INVENTION An object of the present invention is to provide a receiving apparatus and a receiving timing detecting method capable of detecting symbol synchronization timing with high precision according to propagation path conditions even in an environment such as multipath interference. The object of the present invention is a reception device using an orthogonal frequency code multiplexing (OFCDM) transmission method or a multicarrier transmission method, comprising: reception signal information calculating means for calculating reception signal information indicating a reception state of a reception signal, and the reception signal information. And an output synthesizing means for synthesizing in a predetermined section and symbol timing detecting means for detecting symbol synchronizing timing based on the synthesized value.

Multipath, Timing, Symbol, Orthogonal Frequency Code Multiple Division

Description

Receiving device and receiving timing detection method {RECEPTION DEVICE AND METHOD OF RECEPTION TIMING DETECTION}

1 is a block diagram showing a configuration of an OFCDM receiving device which is a receiving device according to an embodiment of the present invention;

2 is a block diagram showing a first embodiment of a symbol synchronization timing detector;

3 is a block diagram showing a second embodiment of the symbol synchronization timing detector;

4 is a block diagram showing a first embodiment of the OFCDM transmitting apparatus;

5 is a diagram illustrating a transmission form of a pilot signal for detecting a first symbol synchronization timing;

6 is a block diagram showing a second embodiment of the OFCDM transmitting apparatus;

7 is a diagram illustrating a transmission form of a pilot signal for detecting second symbol synchronization timing;

8 is a block diagram showing a third embodiment of the OFCDM transmitting apparatus;

9 is a diagram illustrating a transmission form of a pilot signal for detecting third symbol synchronization timing;

10 is a block diagram showing a third embodiment of the symbol synchronization timing detector;

11 is a block diagram showing a fourth embodiment of a symbol synchronization timing detector;

12 is a block diagram showing a fourth embodiment of the OFCDM transmitting apparatus;

13 is a view showing a transmission form of a pilot signal for estimating a propagation path variation value;

14 is a block diagram showing a fifth embodiment of the symbol synchronization timing detector;

15 is a configuration diagram of a symbol synchronization timing detector for explaining a case where symbol synchronization timing is detected by using a combined value of received signal information;

FIG. 16 is a diagram for explaining the case where the maximum value of the correlation output substantially matches the abnormal symbol synchronization timing; FIG.

17 is a diagram for explaining the case where the maximum value of the correlation output is greatly shifted from the abnormal symbol synchronization timing;

18 illustrates a concept of detecting symbol synchronization timing based on a combined value of received signal information;

19 is a block diagram showing a sixth embodiment of a symbol synchronization timing detector;

20 is a diagram showing a first example of a symbol synchronization timing detection method by the symbol synchronization timing detection unit 10 of FIG. 19;

FIG. 21 is a view showing a second example of the symbol synchronization timing detection method by the symbol synchronization timing detection unit 10 of FIG. 19;

FIG. 22 is a view showing a third example of the symbol synchronization timing detection method by the symbol synchronization timing detection unit 10 of FIG. 19;

FIG. 23 is a view showing a fourth example of the symbol synchronization timing detection method by the symbol synchronization timing detection unit 10 of FIG. 19, and

24 illustrates a concept of symbol synchronization timing.

Explanation of symbols for the main parts of the drawings

1: OFCDM receiver

2 ~ 5: OFCDM transmitter

10: symbol synchronization timing detector

11: guide interval remover

12: time-frequency conversion unit (FFT)

13: spread signal generator

14-1 to 14-l, 15-1 to 15-m, 16-1 to 16-n, 55-1 to 55-l, 56-1 to 56-m, 57-1 to 57-n, 75- 1 ~ 75-l, 76-1 ~ 76-m, 77-1 ~ 77-n, 94-1 ~ 94-l, 95-1 ~ 95-m, 96-1 ~ 96-n, 135-1 ~ 135-l, 136-l-136-m, 137-1-137-n: multiplier

17-1 to 17-n: symbol synthesis section

18: parallel-to-serial conversion unit

19: data demodulator

20: Error correction decoder

21: information symbol recovery unit

31, 41, 111, 121, 161, 171: correlation detector

32, 42, 112, 122, 152, 162, 174: output synthesizer

33: maximum received signal power to interference power ratio detection unit

43: maximum received signal power detection unit

50, 71, 90, 130: information signal generator

51, 98: pilot signal generation unit for symbol synchronization timing detection

52, 72, 91, 132: serial-to-parallel conversion unit

53, 73, 92, and 133: spread signal generator

52-1 to 54-m, 74-1 to 74-m, 93-1 to 93-m, 134-1 to 134-m: symbol replica

58, 79, 97, 138, 151: frequency-time conversion unit (IFFT)

59, 80, 99, 139: Guide interval insert

78: information channel and pilot signal synthesis section

110, 170: OFCDM signal generator

113, 123, 153, 163 and 175: Synthetic output maximum detection unit

120: delay circuit

131: a pilot signal generator for estimating propagation path variation

150: propagation path fluctuation estimator

172: path detection unit

173: desired interference replica signal generator

The present invention relates to a receiving apparatus and a receiving timing detecting method used in a mobile communication system, and more particularly, to a receiving apparatus and a receiving timing detecting method using an orthogonal frequency code division multiplex (OFCDM) transmission method or a multi-carrier transmission method.

At present, the wireless transmission method of the 4th generation mobile communication system which aims at higher speed and larger capacity than the 3rd generation mobile communication system (W-CDMA system) is advanced. For example, a multi-carrier code division multiple access (CDMA) system that multiplies spread codes in the frequency axis direction has immunity to frequency selectivity of a propagation path by multipath, which is a problem in mobile communication. In addition, the application to the wireless transmission system of the fourth generation mobile communication system is actively studied (see Non-Patent Document 1, for example).

The Orthogonal Frequency and Code Division Multiplexing (OFCDM) radio transmission scheme is based on the multi-carrier code division multiple access (CDMA) radio transmission scheme, and duplicates information symbols in a time axis direction and a frequency axis direction, and spreads them in each symbol. After multiplying each chip of the code, the spread signal is transmitted in parallel by a plurality of subcarriers with different OFCDM symbols and different frequencies. Therefore, in this system, since the spreading codes are multiplied in the time axis direction and the frequency axis direction as a result, the code multiplexing of a plurality of information channels can be realized by multiplying orthogonal spreading codes.

In addition, since the symbol code is reduced and the symbol length is enlarged by performing parallel transmission using a plurality of subcarriers, the transmitted signal, which is a problem in a mobile communication environment, has a plurality of different propagation paths (multiple). It is possible to reduce the influence of so-called multipath interference, which reaches the receiver at different timing via a path propagation path, and whose signals interfere with each other to degrade characteristics.

Further, at the beginning of each OFCDM symbol, a redundant portion called a guide interval for repeatedly transmitting the portion after the symbol is provided to reduce the influence of symbol interference caused by the multipath propagation path. Can be.

Further, in the multipath propagation path, frequency selective paging occurs in which the variation of the propagation path varies with frequency, and the signal transmission quality changes according to the frequency, but OFCDM spreads the signal in the frequency axis direction, so frequency diversity The signal quality can be improved by the diversity effect.

On the other hand, the received signal of the OFCDM transmission method is input to the fast fourier transform (FFT) to restore information symbols for each subcarrier. The same code as the spreading code multiplied by the transmitting side is multiplied in the time direction and the frequency direction, and despread by combining the received signals of each subcarrier over a spreading code period. Here, the start position of the received signal input to the FFT, so-called symbol synchronization timing, is ideally the end of the guide interval, i.e., the head of the information symbol section of the OFCDM signal as shown in Fig. 24A ((1)). ), A signal of each delay wave coming from the signal section input to the FFT, i.e., the FFT window section (2) (here, signals of delay waves 1 and 2) can be extracted without causing intersymbol interference. Can be.

However, as shown in Fig. 24 (b), when the detected symbol synchronization timing is shifted from the abnormal position due to the influence of the propagation path or the like, interference between symbols is caused in the FFT window section, and neighboring OFCDM signal components are caused. Since they are extracted at the same time, the carrier characteristics deteriorate due to symbol interference. For this reason, it is important to properly estimate the symbol synchronization timing. As a method of detecting the symbol synchronization timing, in the conventional multicarrier transmission in which information symbols are transmitted using a plurality of subcarriers having different frequencies, similar to OFCDM transmission, the guide interval is a repetitive signal later in the multicarrier transmission signal. The method of detecting symbol synchronization timing using the autocorrelation of a repeating part using the thing (refer to nonpatent literature 2, 3) is shown.

Also, from this point of view, a method of inserting a repetitive signal at the head of the information signal section and detecting the symbol synchronization timing by using the autocorrelation of the received signal measured at this portion is shown (for example, Non-Patent Document 4). Reference).

Furthermore, after the mutual correlation between the known pilot signal and the received signal on the receiving side, a position which takes the maximum correlation value is detected from the obtained correlation value column, the correlation value is searched ahead of the position, and any arbitrary The method of detecting as a timing the position of the most correlated value exceeding the threshold of is shown (for example, refer nonpatent literature 5).

Further, in a multi-carrier CDMA type mobile communication system, a plurality of candidates are provided as an optimal base station on the mobile station side, and respective correlations are obtained to detect the FFT timing of the optimal cell and to detect the scramble code. . Thereby, the technique which can detect a spread code at high speed and high precision on the receiving station side is proposed (for example, refer patent document 1).

[Patent Document 1] Japanese Patent Application Laid-Open No. 2003-152681

[Non-Patent Document 1] "Multi-carrier CDMA in indoor wireless radio networks," N. Yee et al., 1993 IEEE Personal and Indoor Mobile Radio Communication

[Non-Patent Document 2] "ML estimation of time and frequency offset in OFDM system," J.-j. v. de Beek, M. Sandell, P. O. Brjesson, IEEE Trans. Signal Proc., Vol. 45, no. 7, pp. 1800-1805, July 1997.

[Non-Patent Document 3] "Optimal Symbol Timing Frequency Offset Estimation Method for Multicarrier Modulated Signals" Kang, Won, Sohn, Young-Young: Theological Report, RCS95-119, pp45-50, January 1996.

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[Non-Patent Document 4] "A fast synchronization scheme of OFDM signals for high-rate wireless LAN" T. Onizawa et al., IEICE Transactions on Communications, vol. E82-B, no. 2, pp. 455-463, Feburary 1999.

[Non-Patent Document 5] "Timing Synchronization Method of OFDM Communication System in Frequency Selective Paging Environment" Pyeong, Seok-Jin, Sam-Taek: Journal of the Institute of Electronics and Information Communication, B Vol. J84-B No. 7 pp. 1255-1264 July 2001

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 However, when the OFCDM transmission scheme is applied to a mobile communication environment, it is difficult to detect ideal symbol synchronization timing due to the influence of multipath interference. In the method described in the non-patent document 2 described above, no consideration has been made assuming multipath interference. In addition, in the conventional method of detecting symbol synchronization timing by using autocorrelation of repeating portions, including Non-Patent Document 3, deviations occur in timing because the correlation sequence is gentle, and a delayed wave having a large power is incident. In this case, there is a problem that the synchronization position is shifted backward. In particular, in a transmission path with a large delay width, since the interference occurs from the front and rear symbols, the autocorrelation characteristics are greatly deteriorated.

In addition, in the prior art described in Non-Patent Document 4, a method of detecting the maximum value of the autocorrelation output of a received signal and detecting the forward timing as a symbol synchronization timing by a predetermined timing in order to reduce the influence of multipath interference is shown. According to the conventional method, it is necessary to optimize the value of the timing shifted forward in accordance with the propagation path, and it is difficult to flexibly cope with the propagation path situation that changes every moment.

In addition, in the prior art described in Non-Patent Document 5, since a correlation value exceeding a threshold equivalent to 1 / a of the maximum correlation value is searched forward from the position at which the maximum correlation value is taken, a large delay wave with a long delay time is required. If present, the received power after FFT cannot be maximized, resulting in increased symbol interference. In addition, since the optimum threshold value varies greatly depending on the transmission path model, it is necessary to optimize the value of the threshold value, and it is difficult to flexibly cope with the fluctuation of the air path condition that is constantly changing.

On the other hand, although the conventional example described in Japanese Patent Laid-Open No. 2003-152681 discloses that the FFT timing of an optimal cell can be detected by providing a plurality of candidates as a base station, this prior art describes all subcarriers before performing the FFT. The FFT timing is obtained by the timing of obtaining the maximum correlation value for detecting the correlation between the received signal containing the component and the synchronization signal replica, and is not synthesized so as to maximize the correlation value after the FFT. Therefore, it is considered difficult to detect the symbol synchronization timing with good accuracy.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is a receiving apparatus capable of detecting symbol synchronization timing with high detection accuracy in accordance with a propagation path even in an environment such as multipath interference. And a reception timing detection method.

In order to solve the above problems, the receiving apparatus of the present invention is a receiving apparatus using an orthogonal frequency, code division multiplex (OFCDM) transmission scheme or a multicarrier transmission scheme, the reception signal for calculating reception signal information indicating a reception state of a reception signal. And information synthesizing means, output synthesizing means for synthesizing the correlation detected correlation value based on the received signal information in a predetermined section, and symbol timing detecting means for detecting symbol synchronization timing based on the synthesized value. It is done.

According to one embodiment of the present invention, the symbol timing detecting means detects the symbol period timing such that the received signal power to interference power ratio or received power after FFT is maximized using the value synthesized by the output synthesizing means.

According to one embodiment of the invention, the received signal information calculating means calculates a cross correlation value of a known pilot signal as the received signal information.

According to one embodiment of the present invention, the received signal information calculating means calculates the autocorrelation value of the received signal as the received signal information.

According to one embodiment of the present invention, the received signal information calculating means calculates a propagation path variation estimate estimated based on a known pilot signal transmitted by the transmitting side as the received signal information.

According to an embodiment of the present invention, the receiving apparatus includes replica signal generating means for generating a replica signal of a desired signal and an interference signal based on the calculation result of the received signal information, and the output synthesizing means comprises the replica signal. Are synthesized in a predetermined section, and the symbol timing detecting means detects symbol synchronization timing using the synthesized replica signal.

According to an embodiment of the present invention, the output synthesizing means uses a plurality of delayed wave reception timings as a plurality of symbol synchronization timing candidates in a received signal, and uses the replica signal generated by the replica signal generation means in the plurality of symbol synchronizations. Synthesized at predetermined intervals of each of the timing candidates, the symbol timing detecting means detects, as symbol synchronization timings, a timing at which the combined value of the replica signal is maximum among the plurality of symbol synchronization timing candidates.

Alternatively, the output synthesizing means sets a timing of shifting a plurality of delay wave reception timings from a received signal by a predetermined amount as a plurality of symbol synchronization timing candidates, and uses the replica signal generated by the replica signal generating means to generate the plurality of symbol synchronization timings. Synthesized at predetermined intervals of the candidates, the symbol timing detecting means detects, as symbol synchronization timings, a timing at which the combined value of the replica signal is maximum among the plurality of symbol synchronization timing candidates.

Or the output synthesizing means sets a timing of shifting the at least one delayed wave reception timing in the received signal and another at least one delayed wave reception timing in the received signal as a plurality of symbol synchronization timing candidates, and the replica The replica signal generated by the signal generating means is synthesized in each of the plurality of symbol synchronization timing candidates, and the symbol timing detecting means sets a timing at which the combined value of the replica signal is maximized among the plurality of symbol synchronization timing candidates. Detection is performed as symbol synchronization timing.

According to an embodiment of the present invention, the symbol timing detecting means includes an SIR estimating means for estimating the received signal power to interference power ratio after the FFT using the synthesized replica signal, and symbol synchronization is performed based on the estimation result. Detect timing.

The reception timing detection method of the present invention is a reception timing detection method in a reception apparatus using an orthogonal frequency code division multiplex (OFCDM) transmission method or a multicarrier transmission method, which calculates reception signal information indicating a reception state of a reception signal. And a step of synthesizing the correlation detected correlation value in a predetermined section based on the received signal information, and detecting a symbol synchronization timing based on the synthesized value.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described based on drawing.

1 is a block diagram showing the configuration of an OFCDM receiving apparatus to which the OFCDM transmission scheme as a receiving apparatus according to an embodiment of the present invention is applied. In this case, the OFCDM transmission scheme is used to duplicate an information symbol in parallel in a time direction and a frequency direction, multiply a spreading code in a time axis direction and a frequency axis direction with respect to the duplicated information symbol, and spread each symbol with a different time. A method of transmitting a signal by a plurality of subcarriers having a plurality of symbols and different frequencies. In addition, this OFCDM transmission scheme is one of representative multiple schemes using a plurality of carriers in a downlink channel in a mobile communication system.

In the figure, the OFCDM receiving apparatus 1 includes a symbol synchronization timing detector 10, a guide interval canceler 11, a time / frequency converter (FFT) 12, a spread signal generator 13, , Multipliers 14-1 to 14-l, 15-1 to 15-m, 16-1 to 16-n, symbol synthesizing units 17-1 to 17-n, and parallel to serial conversion unit 18 And a data demodulation unit 19, an error correction decoding unit 20, and an information symbol recovery unit 21.

In the present embodiment, when the received OFCDM signal is input to the timing detection circuit 10 (hereinafter referred to as a symbol synchronization timing detection unit), the symbol synchronization timing is detected by the timing detection circuit 10. Thereafter, the guide interval is removed by the guide interval removing unit 11, and the received OFCEM signal is separated into components of each subcarrier frequency by the time and frequency converter FFT. Then, the multipliers 14-1 to 16-n spread the spread signals (spread codes generated by the spread signal generator 13) corresponding to each information channel on the time axis and the frequency axis, and then the symbol synthesizer. The signals before spreading are restored by inputting into (17-1 to 17-n) and synthesizing the symbols over the spreading period. The signal restored in this manner is serial-to-parallel converted by the parallel-to-serial conversion unit 18, data demodulation by the data demodulation unit 19, and error correction decoding by the error correction decoding unit 20. The information signal transmitted from the restoration unit 21 is restored.

Next, the symbol synchronization timing detector shown in FIG. 1 will be described. 2 is a block diagram showing a first embodiment of a symbol synchronization timing detector.

In the figure, the symbol synchronization timing detection unit 10 according to the first embodiment includes a correlation detection unit 31, an output synthesis unit 32, and a reception signal power-to-interference power ratio maximum detection unit 33. The function of detecting symbol synchronization timing is maximized so that the received signal power to interference power ratio after the FFT is maximized. In this embodiment, an example before the OFCDM received signal is input to the guide interval canceling unit 11 is shown.

The operation of the symbol synchronization timing detector configured as described above will be described. The received OFCDM signal is input to the correlation detector 31, and the output correlation unit 32 synthesizes the obtained correlation output over a predetermined period. Then, the timing at which the received signal power to interference power ratio is maximized by the received signal power to interference power ratio detection unit 33 is detected as symbol synchronization timing.

3 is a block diagram illustrating a second embodiment of the symbol synchronization timing detector shown in FIG. 1.

As shown in the figure, the symbol synchronization timing detection unit 10 according to the present embodiment includes a correlation detection unit 41, an output synthesis unit 42, and a reception signal power maximum detection unit 43. Has a function of detecting symbol synchronization timing so that the received signal power after the FFT is maximized. In addition, this embodiment shows an example before the OFCDM received signal is input to the guide interval removing unit 11 as in the case of FIG. 2 described above.

The operation of the symbol synchronization timing detector configured as described above will be described. The received OFCDM signal is input to the correlation detector 41, and the obtained output is synthesized by the output synthesizer 42 over a predetermined period. Thereafter, the reception signal power maximum detection unit 43 detects the timing at which the reception signal power is maximized as the symbol synchronization timing.

Fig. 4 is an apparatus of the transmitting side in the case of transmitting a pilot signal for detecting symbol synchronization timing separately from an information signal, in order to detect symbol synchronization timing using a correlation value of a received signal to a symbol synchronization timing detection unit of an OFCDM receiving apparatus. It is a block diagram which shows the structure of the OFCDM transmitter.

In the figure, this OFCDM transmission device 2 includes an information signal generator 50, a pilot signal generator 51 for symbol synchronization timing detection, a parallel parallel switching unit 52, and a spread signal generator 53. And the symbol duplication unit 54-1 to 54-m, the multiplication units 55-1 to 57-n, the frequency / time exchanger (IFFT) 58, and the guide interval insertion unit 59. It is composed.

In the present embodiment, the information signal generated by data modulation in the information signal generator 50 and the pilot signal generated in the pilot signal generator 51 for symbol synchronization timing detection are in the same order, that is, the serial to parallel converter 52. After the serial-to-parallel conversion in the above), the duplication in the time axis direction and the frequency axis direction in the symbol replica units 54-1 to 54-n, the spread signal generator 53 and the multipliers 55-1 to 57-n are performed. Multiplication of the spread signal in the time-axis direction and the frequency-axis direction, and the frequency-time conversion processing by the frequency-time conversion unit (IFFT) 58. When the frequency-time converting process is performed in the frequency-time converting unit (IFFT) 58, it is converted into an OFCDM signal. In addition, the transmission form of a pilot signal may be a transmission form added to an information signal, and may be transmitted in a signal form separate from an information signal.

FIG. 5 is a diagram illustrating a transmission form of a pilot signal for symbol synchronization timing detection transmitted to the OFCDM transmission device shown in FIG. 4. As shown in the figure, in the present embodiment, an information signal section and a pilot signal section are multiplexed in time in the pilot signal for symbol synchronization timing detection.

4 and 5 illustrate an embodiment in which the pilot signal for symbol synchronization timing detection is multiplexed in time, but is not limited to this embodiment. For example, the embodiment shown in FIGS. 6 and 7 is illustrated. As shown in the figure, an information signal (signal of information channels # 1 to #n in this example) and a pilot signal for symbol synchronization timing detection may be multiplied by different spread codes, and may be a code multiplex configuration. As shown in the illustrated embodiment, a frequency-time conversion unit (IFFT) 97 may input a pilot signal for symbol synchronization timing detection and multiplex the multiplexing pilot signal at a specific subcarrier frequency.

In addition, the pilot signal may take the configuration of a common pilot signal multiplied by a common spreading code in all information channels, or may take the configuration of an individual pilot signal multiplied by an individual spreading code for each information channel.

Fig. 10 shows the OFCDM reception using the cross-correlation value of the received signal as the transmission signal information when the pilot signal for symbol synchronization timing detection is transmitted in the OFCDM transmission apparatus in any of Figs. Fig. 1 is a block diagram showing the configuration of the symbol synchronization timing detector of the apparatus.

In the figure, this symbol synchronization timing detector 10 is composed of an OFCDM signal generator 110, a correlation detector 111, an output synthesizer 112, and a synthesized output maximum detector 113. In this embodiment, an example before the OFCDM received signal is input to the guide interval removing unit 111 is shown.

In this embodiment, first, a known pilot signal is input to the OFCDM signal generator 110, and a reference OFCDM signal is generated. In the correlation detector 111, a cross correlation output between the generated reference OFCDM signal and the pilot signal section of the received OFCDM signal is obtained. In this way, the cross-correlation output obtained by the correlation detector is synthesized over a predetermined period by the output synthesizer 112, and the symbol synchronization timing at which the synthesized output is maximized by the synthesized output maximum value detector 113 is detected.

In the embodiment shown in FIG. 10, the function of detecting symbol synchronization timing using the cross-correlation value of the received signal as the received signal information is illustrated. In the embodiment shown in FIG. 11, the symbol synchronization timing detection unit of the OFCDM receiving device receives the received signal. It has a function of detecting symbol synchronization timing using the guide interval section of the received OFCDM signal as signal information.

In the figure, this symbol synchronization timing detector 10 is composed of a delay circuit 120, a correlation detector 121, an output synthesizer 122, and a synthesized output maximum value detector 123. In addition, in this embodiment, the example before an OFCDM received signal is input to the guide interval removal part 11 is shown.

In the present embodiment, the received OFCDM signal is input to the delay circuit 120 and the correlation detector 121. In the delay circuit 120, for example, a delay time of time T is set. The received OFCDM signal and the output signal of the delay circuit 120 are input to the correlation detector 121, and the autocorrelation output between the guide interval section and the information symbol section is obtained. In this way, the autocorrelation output obtained by the correlation detector 121 is synthesized over a predetermined period by the output combiner 122, and the symbol synchronization timing at which the synthesized output is maximized by the synthesized output maximum value detector 123 is detected.

Fig. 12 shows an OFCDM transmitter in the case where a known pilot signal for estimating the propagation path variation is transmitted separately from the information signal in order to detect the symbol synchronization timing by using the estimation value of the propagation path variation in the symbol timing detection unit of the OFCDM receiving apparatus. It is a block diagram which shows the structure of.

In the figure, this OFCDM transmitter 5 includes an information signal generator 130, a pilot signal generator 131 for estimating propagation path fluctuation values, a serial-to-parallel converter 132, and a spread signal generator 133. And a symbol duplication unit (134-1 to 134-m), multipliers (135-1 to 137-n), a frequency-time conversion unit (IFFT) 136, and a guide interval insertion unit 139. do.

In the present embodiment, the information signal generated by data modulation in the information signal generator 130 and the pilot signal generated in the propagation path fluctuation estimation pilot signal generator 131 are in the same order, that is, the serial to parallel converter 52. Serial-to-parallel conversion, symbol replication units 134-1 to 134-m in the time axis direction and the frequency axis direction, and spread signal generating unit 133 and multipliers 135-1 to 137-n. Multiplication of the spread signal in the time axis direction and the frequency axis direction, and frequency / time conversion processing by the frequency / time modulator (IFFT) 138 are performed. When the frequency-time conversion process is performed in the frequency-time conversion unit (IFFT) 138, it is converted into an OFCDM signal. In addition, the transmission form of a pilot signal may be a transmission form added to an information signal, and may be transmitted in a signal form separate from an information signal.

FIG. 13 is a diagram illustrating a transmission mode of a propagation path variation estimation pilot signal transmitted by the OFCDM transmitter shown in FIG. 12. As shown in the figure, in the present embodiment, the pilot signal for estimating the propagation path variation value is multiplexed in time between the information signal section and the pilot signal section, but the information signal and the pilot signal are different from each other in the embodiment shown in FIGS. 6 and 7. It may be a configuration of code multiplexing which is spread by multiplexing by a spreading code or may be a configuration of frequency multiplexing in which a pilot signal is multiplexed to a specific subcarrier frequency as in the embodiments shown in Figs.

The propagation path fluctuation estimation pilot signal may have a configuration of a common pilot signal multiplied by a spread code common to all information channels, or a configuration of a separate pilot signal multiplied by an individual spread code for each information channel.

FIG. 14 is a symbol synchronization of an OFCDM receiving apparatus for estimating a propagation path variation based on a pilot signal for estimating a propagation path variation value transmitted from the OFCDM transmitter shown in FIG. 12 and using the estimated value. It is a block diagram which shows a structure of a timing detector.

In the figure, the symbol synchronization timing detection unit 10 includes a propagation path fluctuation estimation unit 150, a frequency-time conversion unit (IFFT) 151, an output synthesis unit 152, and a combined output maximum value detection unit 153. It consists of. In the present embodiment, an example before the OFCDM received signal is input to the guide interval removing unit 11 is shown.

In the present embodiment, first, the signal interval of the propagation path variation estimation pilot signal received by the propagation path variation estimation unit 150 under the influence of the propagation path variation received by the signal transmitted between the OFCDM transmission apparatus and the OFCDM receiving apparatus. Estimate for each subcarrier frequency using This can be estimated from the fluctuation amount of the signal using the point that the pilot signal for estimation such as the propagation path fluctuation value is known in amplitude, phase and pattern.

As described above, the propagation path variation value for each subcarrier frequency estimated by the propagation path variation estimation unit 150 is input to the frequency-time conversion unit (IFFT) 151, and the impulse response of the propagation path, that is, the complex delay profile Is saved. The delay profile thus obtained, i.e., the propagation path variation for each subcarrier frequency, is synthesized in the output synthesizing unit 152 over a predetermined period, and the symbol synchronizing timing at which the synthesizing output is maximized in the synthesizing output maximum value detecting unit 153 is obtained. Is detected.

As described above, the present embodiment exemplifies an aspect in which the delay profile is obtained from the propagation path fluctuation values for each subcarrier, but the propagation path delay profile may be directly obtained using the pilot signal for propagation path fluctuation value estimation.

FIG. 15 is a configuration diagram illustrating a symbol synchronization timing detector for explaining a case where symbol synchronization timing is detected using a value obtained by combining the received signal information over a predetermined period. As shown in the figure, the symbol synchronization timing detector 10 includes a correlation detector 161, an output synthesizer 162, and a synthesized output maximum value detector 163.

In general, the OFCDM signal is a signal obtained by polymerizing the information signals of the respective subcarriers, and according to the central limit theorem, the signal waveform becomes a signal of Gaussian noise. For this reason, the received signal information shown in the above-described embodiment of Figs. 10 to 12 (as the received signal information, (1) cross-correlation value of known pilot signal, (2) autocorrelation value of received signal, (3) In using the channel estimate as received signal information), when the delay width of the received signal in the multipath propagation path is small, as shown in FIG. 16, the maximum value of the correlated output almost coincides with the abnormal symbol synchronization timing. Therefore, it is possible to detect appropriate symbol synchronization timing by estimating the timing at which the correlation output is maximized.

In general, however, in the multipath propagation path, as shown in FIG. 17, a delay width of a received signal may increase due to geographical conditions of the communication path or the like. Therefore, in such a case, since the probability that the maximum value of the correlation output greatly shifts from the abnormal symbol synchronization timing becomes high, there is a problem of causing inter-symbol interference.

In the present invention, as shown in Fig. 18, the obtained synthesis signal is synthesized over a certain period by the output synthesizing unit 162, and the synthesizing start position at which the synthesizing value output is maximized is the synthesizing maximum detection unit. Detected at 163, symbol synchronization timing is performed. Thus, even when the timing of the maximum value of the correlated output is greatly shifted from the abnormal symbol synchronization timing due to the influence of multipath interference, the power of the direct wave component and the delay wave component of the OFCDM signal 1 symbol can be as much as possible in the FFT window period. Since symbol synchronization timing can be detected depending on the propagation path conditions so as to ensure the interference, interference from adjacent symbols can be reduced.

Fig. 19 is a block diagram showing a configuration of a symbol synchronization timing detector having a function of generating a desired signal and an interference signal replica signal using the received signal information, and detecting symbol synchronization timing using the replica signal.

In the figure, the symbol timing detector 10 includes the OFCDM signal generator 170, the correlation detector 171, the path detector 172, the desired interference replica signal generator 173, and the output synthesizer 174. ) And a combined output maximum value detector 175.

An example of the operation of the symbol synchronization timing detector 10 configured as in FIG. 19 will be described with reference to FIG. 20. 20 is a diagram showing a first example of a symbol synchronization timing detection method in the present embodiment.

20 illustrates an example of estimating received signal power and interference power ratio using the received signal information of (1).

In this embodiment, the correlation detector 171 creates a delay profile based on the cross correlation value between the reference pilot signal generated by the OFCDM signal generator 170 and the received OFCDM signal. The delay profile is a delay time for each received wave as a short pulse, with the horizontal axis as the propagation delay time (= delay time) of the radio wave coming from the receiving side (OFCDM receiving device in this example) and the receiving power as the vertical axis. It is shown on the axis. 20 (1) shows an example of the delay profile in the present embodiment.

The delay profile created as described above is input to the path detector 172, and the path detector 172 detects a large delay wave component (path) of signal power by threshold determination. In this example, it is assumed that L paths are detected.

The desired interference replica signal component 173 includes the power values Si (i = 1, 2, ..., L) of each of the L paths detected by the path detector 172 and the relative delay time Di (i from the leading path. Signal replica with (D _L + N _FFT + N _GI ) number of samples per pass using = 1, 2, ..., L),

Create Here, N _FFT and N _GI represent the number of samples of the FFT window interval and the guide interval interval, respectively. but,

Is D _i ≤ τ ≤ D _i + N _FFT + N _GI ,

And at the timing of the guitar,

Shall be. In addition, L signal replicas,

The desired signal replica S (?) Is obtained by synthesizing a for each sample.

In addition, the interference signal replica I (τ) obtains a sample value max {S (τ)} having a maximum value among (D _L + N _FFT + N _GI ) samples of the desired signal replica S (τ), and I (τ) = max {S (τ)} − S (τ).

The output synthesizer 174 synthesizes S (τ) and I (τ) obtained as described above in the FFT window section, and estimates the SIR of the received signal after the FFT by the following equation.

The maximum synthesis output detector 175 detects the sample timing τ _max at which the estimated SIR τ is maximized as the symbol synchronization timing, and outputs the result to the FFT.

21 is a diagram showing a second example of the symbol synchronization timing detection method by the symbol synchronization timing detection unit 10 of FIG.

 As described above, the correlation detector 171 creates a delay profile and inputs it to the path detector 172. The path detector 172 detects L delay wave components (paths).

The desired and interference replica signal generation unit 173 creates a signal replica for each pass. Further, by synthesizing the L signal replicas for each sample, the desired signal replica S (?) Is obtained, and the interference signal replica I (?) Is obtained.

The output synthesizing unit 174 determines the reception timing of each delayed wave (pass) whose delay times are D1, D2, ..., D _i , ..., D _L. The candidate signal replica S (τ) and the interference signal replica I (τ) generated by the desired and interference replica signal generation unit 173, and symbol synchronization. Synthesis is performed at predetermined intervals relating to each of the candidate 1, candidate 2, ... candidate i, ... candidate L of the timing, for example, the FFT window interval of each path.

The synthesis output maximum value detection unit 175 detects, as symbol synchronization timing, a symbol synchronization timing candidate for which the combined value of the replica signal obtained in the FFT window section of each path is maximum.

22 is a diagram showing a third example of the symbol synchronization timing detection method by the symbol synchronization timing detection unit 10 of FIG.

As in the symbol synchronization timing detection method shown in FIG. 21, the correlation detection unit 171 creates a delay profile and inputs it to the path detection unit 172. FIG. The path detection unit 172 detects L paths (delay wave components). The desired and interference replica signal generation unit 173 obtains the desired signal replica S (τ) and the interference signal replica I (τ).

The output synthesizing unit 174 is a timing for delaying the reception timing of each delayed wave (pass) whose delay times are D1, D2, ..., D _i , ..., D _L , for example, a guide. The timing delayed by the guard interval is set by the symbol synchronization timing candidates (candidate 1, candidate 2, ..., candidate i, ... candidate L), and is generated by the hope and interference replica signal generation unit 173. The predetermined desired signal replica S (?) And the interference signal replica I (?) Are given in a predetermined section, eg, for each of candidate 1, candidate 2, ..., candidate i, ... candidate L of symbol synchronization timing. For example, it synthesizes in the FFT window section of each pass.

The synthesis output maximum value detection unit 175 detects, as symbol synchronization timing, a symbol synchronization timing candidate for which the combined value of the replica signal obtained in each path FFT window section becomes the maximum.

Further, by combining the methods shown in Figs. 21 and 22, symbol synchronization timing can be detected.

FIG. 23 is a diagram showing a fourth example of the symbol synchronization timing detection method by the symbol synchronization timing detection unit 10 shown in FIG.

21, like the symbol synchronization timing detection method shown in FIG. 22, the correlation detection unit 171 creates a delay profile and inputs it to the path detection unit 172. FIG. The path detection unit 172 detects L paths (delay wave components). The desired and interference replica signal generation unit 173 obtains the desired signal replica S (τ) and the interference signal replica I (τ).

In the delay profile of FIG. 23, D _L in the delay time D _i is exceeded by the guide interval section when viewed from the leading path (delay time D1), and delay time D2 is exceeded by the guide interval section when viewed from the leading path. not.

As shown in Fig. 23, the output synthesizing unit 174 sets, for example, the reception timing of a delay wave (pass) having a delay time of D1 as a symbol synchronization timing candidate (candidate 1). In this case, the delay time is a symbol synchronization timing candidate (candidate 2) in which any path reception timing, for example, the timing of delaying D _i by a predetermined interval, for example, the delay of the guide interval, is exceeded. Also, for example, the timing of delaying the reception timing of the delay wave corresponding to the delay time D _L exceeding the guide interval interval by a certain period, for example, the timing delayed by the guide interval, is symbol synchronization timing candidate ( Candidate L). The output synthesizing unit 174 selects the desired signal replica S (τ) and the interference signal replica I (τ) created by the desired / interference replica signal generation unit 173 using the above timing candidates. Synthesized in a predetermined section of each of candidates 2, ..., candidate L, for example, an FFT window section of each pass.

The synthesis output maximum value detection unit 175 detects, as symbol synchronization timing, a symbol synchronization timing candidate for which the combined value of the replica signal obtained in the FFT window section of each path is maximum.

In other words, according to the present embodiment, the symbol synchronization timing in which the power of the direct wave component and delay component of the OFCDM signal 1 symbol in the FFT window period is as much as possible, and the symbol synchronization timing is made as small as possible can be affected by the symbol interference. It becomes possible to detect according to the radio wave condition. Therefore, even when the timing of the maximum value of the correlation output is greatly shifted from the abnormal symbol synchronization timing due to the influence of multipath interference, high-precision symbol synchronization can be realized.

In addition, in this embodiment, although the aspect which used the cross-correlation value of a known pilot signal was illustrated as received signal information, you may use the autocorrelation value of a received signal and the channel estimate estimated from the received signal.

Although each of the above embodiments exemplifies an aspect of the OFCDM receiving apparatus to which the OFCDM transmission scheme is applied as one suitable example, the present invention also applies to a receiving apparatus to which the multi-carrier transmission scheme in which information symbols are transmitted by a plurality of subcarriers having different frequencies. Can be applied.

In the above embodiment, the aspect of detecting the symbol synchronization timing so as to increase the received signal power after the FFT is illustrated, but the received signal power may be obtained by actual measurement or may be estimated using a propagation path profile or the like.

Also, as the received signal information, an aspect in which the symbol synchronization timing is detected so as to maximize the reception quality after the FFT using reception quality information (or communication quality information), for example, BER (bit error rate) or the like, is also considered.

According to the embodiment of the present invention, in the OFCDM transmission or the multi-carrier transmission, when there is multipath interference, it is possible to detect an appropriate symbol synchronization timing according to the propagation path situation, and the intersymbol interference accompanied by timing misalignment. Can be reduced. As a result, it is possible to improve the signal transmission characteristic.

Claims (11)

In a receiving apparatus using an orthogonal frequency, code division multiplex (OFCDM) transmission method or a multicarrier transmission method, Received signal information calculating means for calculating received signal information indicating a reception state of the received signal; Output synthesizing means for synthesizing the correlation detected correlation value in a predetermined section based on the received signal information; Symbol timing detecting means for detecting symbol synchronization timing based on the synthesized value, And the symbol timing detecting means detects the symbol synchronization timing such that the received signal power to interference power ratio or received power after FFT is maximized using the value synthesized by the output synthesizing means. delete The receiving device according to claim 1, wherein the received signal information calculating means calculates a cross correlation value of a known pilot signal as the received signal information. The receiving device according to claim 1, wherein said received signal information calculating means calculates an autocorrelation value of a received signal as said received signal information. The receiving signal information calculating means according to claim 1, wherein the received signal information calculating means calculates, as the received signal information, a propagation path variation estimate estimated based on a known pilot signal transmitted by a transmitting side. Device. In a receiving apparatus using an orthogonal frequency, code division multiplex (OFCDM) transmission method or a multicarrier transmission method, Received signal information calculating means for calculating received signal information indicating a reception state of the received signal; Output synthesizing means for synthesizing the correlation detected correlation value in a predetermined section based on the received signal information; Symbol timing detecting means for detecting symbol synchronization timing based on the synthesized value, The symbol timing detecting means detects the symbol synchronization timing such that the received signal power to interference power ratio or received power after FFT is maximized using the value synthesized by the output synthesizing means, A replica signal generating means for generating a replica signal of a desired signal and an interference signal based on the calculation result of the received signal information, The output synthesizing means synthesizes the replica signal in a predetermined section, And the symbol timing detecting means detects symbol synchronization timing using the synthesized replica signal. 7. The apparatus according to claim 6, wherein the output synthesizing means makes a plurality of delay wave reception timings in a received signal a plurality of symbol synchronization timing candidates, A replica signal generated by the replica signal generating means is synthesized in a predetermined section of each of the plurality of symbol synchronization timing candidates, And the symbol timing detecting means detects, as a symbol synchronization timing, a timing at which a combined value of the replica signals becomes maximum among the plurality of symbol synchronization timing candidates. 7. The apparatus according to claim 6, wherein the output synthesizing means sets a timing of shifting a plurality of delayed wave reception timings from a received signal by a predetermined amount as a plurality of symbol synchronization timing candidates, A replica signal generated by the replica signal generating means is synthesized in a predetermined section of each of the plurality of symbol synchronization timing candidates, And the symbol timing detecting means detects, as a symbol synchronization timing, a timing at which a combined value of the replica signals becomes maximum among the plurality of symbol synchronization timing candidates. The plurality of symbol synchronization timing candidates according to claim 6, wherein the output synthesizing means selects a timing obtained by shifting the at least one delayed wave reception timing in the received signal and the other at least one delayed wave reception timing in the received signal by a predetermined amount. With A replica signal generated by the replica signal generating means is synthesized in a predetermined section of each of the plurality of symbol synchronization timing candidates, And the symbol timing detecting means detects, as a symbol synchronization timing, a timing at which a combined value of the replica signals becomes maximum among the plurality of symbol synchronization timing candidates. 7. The apparatus of claim 6, wherein the symbol timing detecting means comprises SIR estimating means for estimating a received signal power to interference power ratio after FFT using the synthesized replica signal, and detecting symbol synchronization timing based on the estimation result. A receiving device, characterized in that. A reception timing detection method in a receiving apparatus using an orthogonal frequency code division multiplex (OFCDM) transmission method or a multicarrier transmission method, Calculating the received signal information indicating the reception state of the transmission signal; Synthesizing a correlation detected correlation value in a predetermined section based on the received signal information; Detecting symbol synchronization timing based on the synthesized value; And the symbol timing detection step detects symbol synchronization timing such that the received signal power to interference power ratio or received power after FFT is maximized using the values synthesized by the output synthesis process.

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